The present invention relates to a clad metal column for a linear motor which is used for elevators, etc., driven by a linear motor, and the method of manufacturing thereof.
In recent years, elevators driven by a linear motor have been developed, and those linear-motor-driven elevators have employed clad metal columns, each of which consists of a magnetic steel column whose periphery is shielded with an aluminum pipe which is a good conductor. And, in manufacturing said clad metal column, a steel column is shielded with an aluminum pipe which is cladded by shrinkage fit or chilled fit.
However, in the actual use of the above-mentioned clad metal column, there has been a problem that the core material and the aluminum pipe are liable to separate in the longitudinal direction caused by the shearing force due to the thrust force generated thereon.
Further, if the bonding force between the core material and the aluminum pipe is deficient in the practice of employing a screw connection for connecting a large number of clad metal columns, a twisting torque is applied to the outer aluminum pipe and, as a result, only the outer aluminum pipe rotates and a sufficient torque cannot be transmitted to the inner core material.